Past research shows that both teachers' technological pedagogical content knowledge (TPACK) and their engagement in metacognitive activities are essential to technology integration in the classroom. However, the interplay between teachers' TPACK ability and their metacognitive skills is still underexplored, especially in the context of developing technology-infused lesson plans. This study examined how the interrelations among metacognitive activities and TPACK constructs affected preservice teachers' technology integration in instructional design. Sixty-four preservice teachers designed a lesson with nBrowser, a computer-based learning environment (CBLE) that helps teachers incorporate technology into instruction by promoting self-regulated learning (SRL). Drawing on the lesson plans, we extracted six types of metacognitive processes preservice teachers exhibited while solving the task and generated two distinct SRL profiles according to the identified latent profile of metacognitive patterns. The competent self-regulated learners demonstrated more efforts in metacognitive monitoring activities than the less competent self-regulated learners in regulating their task solving processes. When comparing TPACK comprehension and design performance between the two profiles, the competent self-regulated learners outperformed the less competent self-regulated learners on comprehension and design outcomes. This study provides deep insights into teachers' self-regulation in CBLEs and emphasizes the pivotal role of metacognition and SRL in teachers' TPACK development.